AU2021107658A4 - Expandable Blast Hole Stemming Device - Google Patents

Abstract

A blast hole stemming device for use in a blast hole, the device comprising: an expandable container for receiving a fluid such that pressurisation of fluid in the container causes the container to expand; a closure for sealing the container; and a coupler for coupling the container to a fluid source so that fluid may be received in the container. - 5/5 10 14 20 46 44 4 40 32 FIGURE 9 16 54 10 56 56 16 52 12 FIGURE 10

Description

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Expandable Blast Hole Stemming Device

Field of the Invention

[0001] The present invention relates to stemming devices for use in blast holes and excavation activities.

Background

[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application.

[0003] In some instances of blasting relating to mining and other excavation activities, a blast hole may be drilled in any direction, including horizontal or upwardly angled holes. Explosives may then be placed in the blast hole, covered with stemming material and contained using a plug. The stemming material improves the penetration of the explosion into the layers of earth surrounding the explosives. Without the stemming material a large portion of the energy directed other than into the earth to be blasted, such as out of the entrance of the blast hole. This is known as rifling.

[0004] In the instance of a horizontal or upward blast hole, the plug must be able to support the weight of all or some of the explosive material and stemming material while providing some resistance to the energy from the explosion. This can place logistical limitations on the suitability or form of the explosives and stemming materials. This can result in additional planning, more expensive explosives and stemming material, and additional equipment. In some instances, it is common practice to omit stemming material entirely.

[0005] The stemming material is typically a type of rock or sand, a column of which, in a vertical upward blast hole, would be difficult to maintain. Current solutions are inefficient or insufficient to support columns of explosives and stemming material, let alone provide resistance to an explosion.

[0006] It is against the general background that the current invention is presented.

[0007] Throughout the specification unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0008] Throughout the specification unless the context requires otherwise, the word "include" or variations such as "includes" or "including", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Summary of Invention

[0009] According to a first aspect, there is provided a blast hole stemming device for use in a blast hole, the device comprising:

an expandable container for receiving a fluid such that pressurisation of fluid in the container causes the container to expand;

a closure for sealing the container; and

a coupler for coupling the container to a fluid source so that fluid may be received in the container.

[0010] In an embodiment, the container is coupled to the fluid source by engaging an end portion of the fluid source with the coupler.

[0011] In an embodiment, the closure further comprises a releasable or breakable interference between the closure and the end portion.

[0012] In an embodiment, the releasable interference is configured to automatically release upon reaching a predetermined pressure threshold. In an embodiment, the breakable interference is configured to automatically break upon reaching a predetermined pressure threshold.

[0013] In an embodiment, the end portion can be manually de-coupled from the coupler.

[0014] In an embodiment, the closure closes the container when the breakable interference breaks so as to retain fluid in the container.

[0015] In an embodiment, the closure closes the container when the end portion is de coupled from the coupler.

[0016] In an embodiment, the breakable interference comprises complementary engaging portions.

[0017] In an embodiment, the complementary engaging portions comprise a channel and a projection. Preferably the projection is a breakable projection.

[0018] In an embodiment, the coupler comprises the breakable projection.

[0019] In an alternative embodiment, the end portion comprises the breakable projection.

[0020] In an embodiment, a breaking point of the breakable interface occurs when a pressure at the breakable interface reaches a predetermined threshold.

[0021] In an embodiment, the pressure is due to pressurisation of fluid in the container.

[0022] In an embodiment, the breakable interference comprises a plurality of complementary engaged portions.

[0023] In an embodiment, the closure and the coupler are integrally formed.

[0024] In an embodiment, the closure and the coupler are in the form of a cap.

[0025] In an embodiment, the cap comprises an internally threaded connection.

[0026] In an embodiment, the container comprises an externally threaded connection.

[0027] In an embodiment, the closure further comprises a valve.

[0028] In an embodiment, the valve comprises a non-return valve.

[0029] In an embodiment, the container is coupled to the fluid source by way of a conduit.

[0030] In an embodiment, the conduit is a hose, tube or pipe.

[0031] In an embodiment, the conduit is flexible.

[0032] In an embodiment, the conduit is a hydraulic hose.

[0033] In an embodiment, a body of the container comprises ribs.

[0034] In an embodiment, the ribs provide expansion portions.

[0035] In an embodiment, the body is cylindrical.

[0036] In an embodiment, the ribs are disposed longitudinally parallel with a central axis of the body.

[0037] In an embodiment, the end portion comprises at least one finger extending longitudinally away from the end portion.

[0038] In an embodiment, the end portion of the conduit comprises at least one channel.

[0039] In an embodiment, the at least one channel is positioned on a respective internal surface of the at least one finger of the end portion.

[0040] In an embodiment, the at least one channel extends in an arc of a radius of a longitudinal axis of the end portion.

[0041] In an embodiment, the radius of the longitudinal axis is greater at one end of the channel.

[0042] In an embodiment, the end portion of the conduit comprises a gap is provided between adjacent projections.

[0043] In an embodiment, the gap receives a respective one of the at least one finger.

[0044] In an embodiment, there are a plurality of fingers separated by a corresponding space.

[0045] In an embodiment, the coupler is arranged to be received in the end portion to align the projection adjacent to the channel.

[0046] In an embodiment, the end portion is able to be rotated relative to the coupler to receive the breakable projection within the channel.

[0047] In an embodiment, the channel is curved towards the centre of the end portion.

[0048] In an embodiment, a frictional connection is created when the breakable projection is received within the channel.

[0049] In an embodiment, the frictional connection locks the end portion relative to the coupler.

[0050] In an embodiment, the channel comprises a stop at an end of the channel.

[0051] In an embodiment, the stop limits the rotation of the breakable projection within the channel.

[0052] In an embodiment, the stop prevents overtightening of the end portion.

[0053] In an embodiment, the gap is arranged to receive a wall portion of the channel, the wall portion being slidable with respect to the breakable projection so as to engage the wall portion with the breakable projection, such that when so engaged the end portion remains coupled with the coupler until the breakable projection breaks when the breaking point is reached.

[0054] According to a second aspect of the invention, there is provided a system comprising a blast hole stemming device described herein, an end portion of a conduit connected to a fluid source.

[0055] According a third aspect of the invention, there is provided a method for installing a blast hole stemming device, the method comprising the steps:

inserting an expandable container into a blast hole;

connecting a fluid source such that a fluid can be received by the container;

pressurising the container with the fluid until the pressure at a breakable interference reaches a breaking point thereby breaking the breakable interface;

disconnecting the fluid source;

retaining a fluid in the container after the fluid source is disconnected.

Brief Description of Drawings

[0056] In order to provide a better understanding, preferred embodiments of the invention will now be described with reference to the following drawings, in which:

Figure 1 is an elevation of blast hole stemming device according to an embodiment of the present invention;

Figure 2 is an enlarged view of a cap of the stemming device coupled to an end portion of a fluid supply apparatus according to an embodiment of the present invention;

Figure 3 is an isometric view of the cap of the blast hole stemming device according to an embodiment of the present invention;

Figure 4 is an isometric view of the end portion according to an embodiment of the present invention;

Figure 5 is a side view of the stemming device in a blast hole according to an embodiment of the present invention;

Figure 6 is a cross section view of the stemming device connected to a hydraulic line of the fluid supply apparatus according to an embodiment of the present invention;

Figure 7 is a side view of the stemming device connected to the fluid source and a container thereof inflated to engage walls of a blast hole according to an embodiment of the present invention;

Figure 8 is a cross-sectional of the engagement of the end portion and the cap of the device of Figure 7, according to an embodiment of the present invention;

Figure 9 is a side view of the stemming device installed after de-coupling of the end portion from the cap according to an embodiment of the present invention; and

Figure 10 is an isometric view of an expanded expandable container according to an embodiment of the present invention.

Description of Embodiments

[0057] Referring to Figures 1 and 2 there is provided a blast hole stemming device 50 comprising an expandable container 10 having a plurality of ribs 16 disposed longitudinally parallel with a central axis of the container 10. The container 10 is suitable to receive and contain a fluid. A body 52 of the container 10 comprises the ribs 16 which are able to expand from a collapsed form such as is shown in Figure 1, to accommodate additional fluid into an expanded form such as that shown in Figure 10 (discussed in detail below). An opening 12 of container 10 comprises an external threaded connection on to which a cap 20 comprising an internal threaded connection can be threadedly engaged. Preferably, the body 52 of the container 10 is cylindrical, however, the shape may be elliptical, oblong, oval, tapered, eccentric or otherwise, provided that, as the container 10 expands, it can engage with and form to the shape of its surroundings. Preferably, the container 10 is formed of a thermoplastic polymer resin such as polyethylene terephthalate, otherwise known as PET or PETE. The container 10 may also be formed from other materials, such as high-density polyethylene, otherwise known as HDPE.

[0058] A coupler and a closure are integrally formed into cap 20. Cap 20 comprises the coupler for engaging the stemming device 50 with end portion 40 of a conduit 32 connected to a fluid source 100. The coupler function is discussed in more detail below. The closure is for sealing the container 10 to retain a fluid. The closure may be in the form of a valve, such as silicone flapper valve 34 (seen in Figure 8), which allows fluid to be received within the container 10 and retains said fluid once it has been received. Cap 20 may comprise alternative closure mechanisms which allow fluid to be received and retained such as a check valve, non return valve, reflux valve, retention valve, foot valve, spring-loaded valve or umbrella valve. The closure will allow fluid to flow into the container 10 but resist backflow of the fluid. For example, the silicone flapper valve 34 provides minimal resistance to fluid flow in one direction while also providing resistance to flow in the opposite direction. This resistance to back flow seals the container 10 after fluid flow has ceased. The cap 20 may comprise a combination of the same or different closure mechanisms. The coupler may also comprise a closure which seals the coupler from further fluid spillage.

[0059] In an embodiment, the cap 20 may comprise a closure, such as a silicone flapper valve 34. The cap 20 may also comprise a formation 30 for engaging with the end portion 40 of the conduit 32 to activate the flow of fluid out of the end portion 40 through to the container 10. Preferably, the formation 30 is in the form of a protrusion. The end portion 40 may comprise a valve, such as a spring-loaded ball valve 26, seen in Figure 8. When the cap 20 is received by the end portion 40 the formation 30 may engage with and open the ball valve 26. When the cap 20 and the end portion 40 are separated (as discussed below) the spring-loaded ball valve 26 returns to a closed position and the flow of fluid from the end portion 40 ceases.

[0060] In an alternative embodiment, formation 30 may be part of a coupler that is distinct from cap 20 (including the closure) and the end portion 40. In this embodiment, the cap 20 comprises means to couple to the coupler. The end portion 40 may then be joined to the coupler.

[0061] The stemming device 50 is connected to a fluid source 100 (such as a hydraulic pump or hydraulic ram shown in Figure 6) by way of conduit 32, such as a hydraulic hose, which is connected to the fluid source. The conduit 32 may also be a pipe, tubing or other suitable means for conveying a fluid under a pressure. The conduit 32 comprises the end portion 40 which engages with the coupler of the cap 20 to create a fluid connection between the fluid source 100 and the interior of the body 52 of the container 10.

[0062] As seen in Figure 3, this embodiment of the cap 20 has projections 22 evenly disposed about a rim of the cap 20 to define a plurality of gaps 28.

[0063] Referring to Figure 4, there is provided an embodiment of the end portion 40 which connects the conduit 32 to the cap 20 thereby creating a fluid connection between the fluid source 100 and the interior of the body 52 of the container 10. As discussed above, end portion 40 may comprise a spring-loaded ball valve 26. The cap 20 may comprise the formation 30 which opens the spring-loaded ball valve 26 during engagement of the cap 20 with the end portion 40. When engaged, the formation 30 opens the spring-loaded ball valve 26 such that fluid can flow from the end portion 40 through the cap 20 and into the container 10. The cap 20 engaging side of the end portion 40 comprises at least one finger 44, in this embodiment there is provided four fingers 44 separated by an equal number of spaces 46. The or each finger 44 extends longitudinally away from the conduit 32. Each finger 44 comprises a channel 42 positioned on an internal surface of each finger 44.

[0064] Alternative embodiments of the end portion 40 may comprise more or less fingers 44 and spaces 46 therebetween. For example, end portion 40 may comprise a single finger 44 which extends about half the circumference of end portion 40 and a space 46 which extends the other half of the circumference of end portion 40. Alternative embodiments may comprise 2, 3, 5, 6, 7 etc. number of fingers 44 with equal number of spaces 46 between the fingers 44. In a further alternative, the fingers 40 may be integrally formed with a connecting ring. Preferably, the fingers and connecting ring are formed of stainless-steel.

[0065] The projections 22 are received in the spaces 46 of the end portion 40 until the projections 22 of the cap 20 align with a respective channel 42. In alternative embodiments, the end portion 40 may comprise the projections 22 and the cap 20 may comprise the respective channels.

[0066] Referring to Figure 2, each of the projections 22 are received into the spaces 46 between the fingers 44 of the end portion 40. The projections 22 are spaced apart such that the gaps 28 between each of the projections 22 may receive a respective finger 44 of end portion 40. Each of the projections 22 are receivable until aligned with a respective channel 42 on an internal surface of a respective finger 44.

[0067] When each of the projections 22 are aligned with a respective channel 42, the end portion 40 is rotatable with respect to the cap 20 of the stemming device 50. Each of the respective channels 42 extend in an arc of a radius of a longitudinal axis of the end portion 40. As such, when aligned, the projections 22 are receivable into a respective channel 42. In an embodiment, the radius of the or each channel 42 decreases thereby making each channel 42 shallower at one end relative to its other end. Preferably, in such an embodiment, each end that initially receives a respective projection 22 is deeper relative to the other end. The or each channel 42 therefore has a path which curves towards the longitudinal centre axis of the end portion 40.

[0068] In one embodiment, the cap 20 may further comprise one or more backstops 18. The backstop 18 may be resiliently flexible in a radial direction. As the projections 22 are received into the spaces 46 between the fingers 44 of the end portion 40, each backstop 18 is biased radially inward of the cap 20. As described above, each projection 22 is received into a respective channel 42. When each projection 22 is received in a respective channel 42, each finger 44 rotates past each of the backstops 18. The or each backstop 18 can flex back into a neutral position to lock the or each projection 22 within a respective channel 42. When the or each projection 22 is locked into a respective channel 42, the end portion 40 is coupled to the cap 20. The end portion 40 may be de-coupled by breaking the or each projection 22 from the cap 20 as described herein.

[0069] Alternatively, the engagement of the end portion 40 and the cap 20 is relatively loose initially, however, as each respective channel 42 shallows the engagement of the projections 22 and respective channel 42 tightens due to friction. At or near the end of rotating the projection 22 into the respective channel 42, the end portion 40 may become locked relative to the cap 20. The locking of the end portion 40 relative to the cap 20 refers to a sufficient frictional resistance such that the conveyance of fluid will not cause the end portion 40 rotate in a manner which withdraws the projections 22 from its respective channel 42.

[0070] At or near the end of each channel 42 a respective stop 24 may be positioned to prevent the projections 22 from being received any further within its respective channel 42. Each stop 24 may prevent over rotating the end portion 40 and/or excessive tightening of the end portion 40 to the cap 20. As described below the projections 22 are breakable. For example, they are frangible and/or are connected to the rim of the cap 20 by a narrowed section which is able to be broken.

[0071] In other embodiments the features analogous to the breakable projections 22 and channels 42 may comprise a variety of complementary shapes and/or interfaces. The person skilled in the art would readily appreciate that the present invention encompasses alternative shapes and/or interfaces provided they function as complementary engaging portions. In alternative embodiments, the breakable projections 22 and channel 42 may comprise a different shape.

[0072] Furthermore, in an alternative embodiment, each of the initial ends may have a shallower channel 42 relative to its other end. Such feature would make the initial rotation stiffer but would resist back rotation which would result in de-coupling of the end portion 40 and the cap 20.

[0073] In alternative embodiments, the cap 20 may not be physically breakable but instead could be releasable when a threshold force is reached, such as by use of an annular or segmented snap fit that does not fracture upon release.

[0074] In an embodiment, the recess 28 is arranged to receive a wall portion 48 of the channel 42. The wall portion 48 on the side of the channel 42 distal from the conduit 32 is slidable with respect to the projection 22 so as to engage the wall portion 48 with the projection 22. When so engaged the end portion 40 remains coupled with the coupler until the interference created by the projection 22 and the channel 42 breaks when the breaking point is reached (as described further below).

[0075] Referring to Figure 6, there is shown the stemming device 50 in fluid connection with the fluid source 100 by way of conduit 32. The fluid source 100 may be for example a fluid pump and tank. The fluid may for example be water, although other fluids, such as gases (i.e. air) or other liquids are possible.

[0076] Referring to Figure 7, 8 and 9, as fluid is conveyed into container 10 the interior of the body 52 of the container fills with the fluid. When the fluid fills the container 10, the ribs 16 provide expansion of the container 10. The pressure in the container 10 is due to the pressurisation of fluid. As fluid fills the container 10 the pressure expands the expanded body 52 of the container 10 engages with the blast hole 14. When the container 10 expands to engage with the blast hole 14, a pressure throughout the container 10 and the conduit 32 increases. Each of the breakable projections 22 are configured to have a breaking point at a predetermined threshold.

[0077] Figure 10 shows an embodiment of the body 52 of container 10 in an expanded state. Each rib 16 may comprise at least one curved section 54 and at least one folded section 56 (as seen in Figure 10). In an embodiment, each rib 16 may be placed adjacent to another rib 16 such that when the body 52 of container 10 is in an unexpanded state, the folded portions 56 or each rib fold into each other allowing the adjacent curved sections 54 to meet at their lateral edges. As the body 52 of the container 10 receives fluid, adjacent curved sections 54 are able to separate and unfold the folded portions 56 to accommodate more fluid and radially expand to contact and conform to the shape of a blast hole 14.

[0078] As the pressure in the body 52 of the container 10 and conduit 32 builds, the container 10 and the end portion 40 are urged to separate. In other words, the pressure creates forces in opposite directions with respect to the container 10 and the end portion 40. The breakable projections 22 provide the interference that stops the container 10 and end portion 40 from separating while the forces are lower than the breaking point of the breakable projections 22.

[0079] When the pressure at the coupler and end portion 40 reaches the predetermined threshold, that is when the forces exceed the breaking point of the breakable projections 22, they break and no longer hold the end portion 40 in position with the cap 20. Thus, the break allows the end portion 40 to separate from the cap 20 (seen in Figure 9). The separation of the end portion 40 and the cap 20 thereby disconnects the fluid source 100 from the container 10. The closure of the cap 20 seals the container 10 thereby retaining the fluid inside the interior of the body 52 of the container 10 to maintain the pressure of the body 52 against the wall of the blast hole 14 and thus maintaining the installation of the stemming device 50 in the blast hole 14.

[0080] Referring to the Figures generally, there is provided a system which comprises stemming device 50, the end portion 40 and the fluid source 100. The fluid source is typically connected to the end portion 40 by way of the conduit 32. However, in some instances the end portion 40 may be directly connected to the fluid source 100.

[0081] Alternatively, the end portion 40 may be manually decoupled from the cap 20. To give effect to this, the stemming device 50 may be pressurised to a desired threshold. Once at the desired threshold the conveyance of fluid can be ceased. The closure of cap 20 will retain the fluid within the container 10 to maintain the desired pressure. After the conveyance of fluid is ceased and the closure of cap 20 has sealed the container 10, the end portion 40 can be manually rotated in a reverse manner of installation of the end portion 40 on the cap to de-couple the end portion 40 from the coupler of the cap 20.

[0082] The stemming device 50 will be pressurised to a pressure threshold of at least 35 pounds per square inch (psi) and preferably, greater than 50 psi. The pressure threshold may be a different pressure, such as 10, 20, 30, 40, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300 etc. psi, which is selected according to the amount of retention force desired. The selection may be based on the amount of explosives and stemming material being supported by the stemming device 50. Furthermore, the pressure required may also be varied based on the inclination or the diameter of blast hole 14. An upward blast hole will require relatively more pressure than a slightly inclined blast hole or horizontal blast hole regardless of amount and type of explosives and stemming material. A blast hole 14 having a smaller diameter can have a higher pressure applied to the stemming device 50.

[0083] During installation, the stemming device 50 as described herein is positioned in a blast hole 14. The end portion 40 being in fluid communication with a fluid source is coupled to cap 20 to create a fluid connection between the container 10 and the fluid source. The fluid is pressurised into the container 10 causing expansion to fit the profile of the blast hole 14. The fluid is continued to be pressurised until a predetermined threshold has been reached. Once the pressure reaches a predetermined threshold the breakable interference will reach a breaking point and break. The breaking of the breakable interference will result in the decoupling of the stemming device 50 from the fluid source. The stemming device 50 will be installed in a position within the blast hole 14.

[0084] Modifications may be made to the present invention within the context of that described and shown in the drawings. Such modifications are intended to form part of the invention described in this specification.

[0085] Examples of modifications include but are not limited to the following. In an embodiment, a modular solid medium, such as clay, potash or aggregate, may be added inside and/or outside as a modular addition to the body 52 of the container 10 to improve the initial resistance to heat and shock. In one embodiment, when liquid is used to expand the container 10, upon detonation, the liquid will be released and may act as a dust and/or particle suppressant. In an embodiment, additives which improve dust/particle suppression may be added inside of the body 52 of the container 10 and/or be delivered with liquid being used to expand the container 10. Other potential additives may be used to capture atmospheric contaminants. Furthermore, the container 10 may also comprise additional additives, such as a polyacrylate or similar chemical, which may cause the inflation medium to form a gel. The formation of a gel can prevent liquid from escaping the container and desensitising the explosives. The gel can also have better explosive energy confinement characteristics and better load bearing capacity.

[0086] Preferably, the present invention is used in horizontal or upwardly angled blast holes. However, the stemming device 50 described herein may be used in downwardly angled blast holes as well. Furthermore, the stemming device 50 described herein may be suitable for blasting in downwardly angled blast holes to retain explosives to a smaller zone within a blast hole.

Claims (3)

Claims

1. A blast hole stemming device for use in a blast hole, the device comprising: an expandable container for receiving a fluid such that pressurisation of fluid in the container causes the container to expand; a closure for sealing the container; and a coupler for coupling the container to a fluid source so that fluid may be received in the container.

2. A system for stemming a blast hole comprising the blast hole stemming device according to claim 1, and an end portion of a conduit connected to a fluid source.

3. A method for installing a blast hole stemming device, the method comprising the steps:

inserting an expandable container into a blast hole;

connecting a fluid source such that a fluid can be received by the container;

pressurising the container with the fluid until the pressure at a breakable interference reaches a breaking point thereby breaking the breakable interface;

disconnecting the fluid source;

retaining a fluid in the container after the fluid source is disconnected.

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